CID Retention Device For Li-ion Cell

ABSTRACT

A low pressure current interrupt device (CID) activates at a minimal threshold internal gauge pressure in a range of, for example, between about 4 kg/cm 2  and about 9 kg/cm 2 . Preferably, the CID includes a first conductive plate and a second conductive plate in electrical communication with the first conductive plate, the electrical communication between the first and the second conductive plates being interrupted at the minimal threshold internal gauge pressure. More preferably, the first conductive plate includes a frustum having a first end and a second end, a base extending radially from a perimeter of the first end of the frustum, and an essentially planar cap sealing the second end of the frustum. The first end has a broader diameter than the second end. More preferably, the second conductive plate is in electrical contact with the essentially planar cap through a weld. A battery, preferably a lithium-ion battery, comprises a CID as described above. A method of manufacturing such a CID comprises forming first and second conductive plates as described above, and welding the second conductive plate onto the first conductive plate while a temperature of the first conductive plate is controlled so as not to exceed the melting point of a surface of the first conductive plate opposite the weld.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/214,535, filed Jun. 19, 2008, which claims the benefit of U.S.Provisional Application No. 60/936,825, filed on Jun. 22, 2007. Theentire teachings of the above applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION

Li-ion batteries in portable electronic devices typically undergodifferent charging, discharging and storage routines based on their use.Batteries that employ Li-ion cell chemistry may produce gas when theyare improperly charged, shorted or exposed to high temperatures. Thisgas can be combustible and may compromise the reliability and safety ofsuch batteries. A current interrupt device (CID) is typically employedto provide protection against any excessive internal pressure increasein a battery by interrupting the current path from the battery whenpressure inside the battery is greater than a predetermined value. TheCID typically includes first and second conductive plates in electricalcommunication with each other. The first and second conductive platesare, in turn, in electrical communication with an electrode and aterminal of the battery, respectively. The second conductive plateseparates from (e.g., deforms away or is detached from) the firstconductive plate of the CID when pressure inside the battery is greaterthan a predetermined value, whereby a current flow between the electrodeand the terminal is interrupted.

Generally, however, CIDs known in the art activate at a relatively highpressure, for example, at an internal gauge pressure greater than about15 kg/cm². Typically, when any excessive internal pressure increase thattriggers such CID activation occurs, the internal temperature of thebattery is also relatively high, causing additional safety issues. Hightemperatures are a particular concern in relatively large cells, such ascells larger than “18650” cells (which has an outer diameter of about 18mm and a length of 65 mm).

Therefore, there is a need for CIDs for batteries, particularlyrelatively large batteries, that can reduce or minimize theaforementioned safety issues.

SUMMARY OF THE INVENTION

The present invention generally relates to a low pressure CID, to abattery, such as a lithium-ion battery, comprising such a low pressureCID, to a method of manufacturing such a low pressure CID, and to amethod of manufacturing such a battery. The CID typically includes afirst conductive plate and a second conductive plate in electricalcommunication with the first conductive plate. The electricalcommunication can be interrupted when a gauge pressure between theplates is in a range of, for example, between about 4 kg/cm² and about10 kg/cm² or between about 4 kg/cm² and about 9 kg/cm².

In one embodiment, the present invention is directed to a CID comprisinga first conductive plate and a second conductive plate. The firstconductive plate includes a frustum having a first end and a second end,a base extending radially from a perimeter of the first end of thefrustum, and an essentially planar cap sealing the second end of thefrustum. The first end has a broader diameter than the second end. Thesecond conductive plate is in electrical contact with the essentiallyplanar cap, preferably through a weld.

In another embodiment, the present invention is directed to a battery,preferably a lithium-ion battery, that includes at least one CID asdescribed above. The battery further includes a battery can having acell casing and a lid which are in electrical communication with eachother. The battery further includes a first terminal and a secondterminal. The first and second terminals are in electrical communicationwith a first electrode and a second electrode, of the battery,respectively. In the battery, the base of the CID is proximal to thebattery can, such as the cell casing or the lid, and the essentiallyplanar cap is distal to the cell can. The battery can is electricallyinsulated from the first terminal, and at least a portion of the batterycan is at least a component of the second terminal, or is electricallyconnected to the second terminal.

In yet another embodiment, the present invention is directed to alithium-ion battery comprising a CID that includes a first conductiveplate and a second conductive plate. The second conductive plate is inelectrical communication with the first conductive plate. Thelithium-ion battery further includes a battery can that includes a cellcasing and a lid that are in electrical communication with each other.The first conductive plate of the CID is in electrical communicationwith the battery can. This electrical communication is interrupted whena gauge pressure between the plates is in a range of between about 4kg/cm² and about 9 kg/cm².

The present invention also includes a method of manufacturing a CID. Themethod includes the steps of forming a first conductive plate andforming a second conductive plate. The first conductive plate includes afrustum having a first end and a second end, a base extending radiallyfrom a perimeter of the first end of the frustum, and an essentiallyplanar cap sealing the second end. The first end of the frustum has abroader diameter than the second end of the frustum. The method ofmanufacturing a CID further includes welding the second conductive plateonto the essentially planar cap of the first conductive plate while atemperature of the first conductive plate is controlled so as not toexceed the melting point of a surface of the first conductive plateopposite the weld.

The present invention also includes a method of manufacturing a batteryof the invention as described above. The method includes forming a CIDand attaching either a first electrode or a second electrode of thebattery to the CID. The formation of the CID includes forming a firstconductive plate that includes a frustum, having a first end and asecond end having a diameter less than that of the first end, a baseextending radially from a perimeter of the first end of the frustum, andan essentially planar cap sealing the second end of the frustum. Theformation of the CID further includes forming a second conductive plate,and welding the second conductive plate onto the essentially planar capof the first conductive plate. The welding is performed while atemperature of the first conductive plate is controlled so as not toexceed the melting point of a surface of the first conductive plateopposite the weld. The method further includes attaching the CID to abattery can including a cell casing and a lid, i.e., either to the cellcasing or to the lid. The method further includes forming a firstterminal in electrical communication with the first electrode, and asecond terminal in electrical communication with the second electrode.

A method of manufacturing a lithium-ion battery of the invention, asdescribed above, is also included in the present invention. The methodincludes forming a battery can that includes a cell casing and a lidthat are in electrical communication with each other. A CID is formed.The formation of the CID includes forming a first conductive plate,forming a second conductive plate, and welding the second conductiveplate onto the first conductive plate while a temperature of the firstconductive plate is controlled not to exceed the melting point of asurface of the first conductive plate opposite the weld. The weldconnecting the first conductive plate and the second conductive plateruptures when a gauge pressure between the first and second conductiveplates is in a range of between about 4 kg/cm² and about 9 kg/cm².Either a first electrode or a second electrode of the battery to the CIDis attached to the second conductive plate of the CID. The firstconductive plate of the CID is attached to a battery can (i.e., eitherto the cell casing or to the lid). At least one venting means is formedon the cell casing of the cell can, through which gaseous species insidethe battery exit when an internal gauge pressure of the battery is in arange of between about 12 kg/cm² and about 20 kg/cm². The method ofmanufacturing a lithium-ion battery further includes welding the lidonto the cell casing. The weld connecting the lid and the cell casingruptures when a gauge pressure between the first and second conductiveplates is equal to, or greater than, about 20 kg/cm². In a specificembodiment, the weld connecting the lid and the cell casing ruptureswhen a gauge pressure between the first and second conductive plates isequal to, or greater than, about 23 kg/cm² or about 25 kg/cm². Themethod of manufacturing a lithium-ion battery further includes forming afirst terminal in electrical communication with the first electrode, anda second terminal in electrical communication with the second electrode.

Also includes in the present invention is a battery pack that includes aplurality of batteries as described above.

In the batteries of the present invention, the current interrupt devicecan be activated at a relatively low gauge pressure, e.g., between about4 kg/cm² and about 10 kg/cm², and interrupt internal current flow of thebatteries. Applicants have discovered that, when the low pressure CID ofthe invention activates at a gauge pressure of between about 4 kg/cm²and about 10 kg/cm², the average cell skin temperature in lithium-ionbatteries, which have a prismatic “183665” configuration and employ amixture of Li_(1+x)CoO₂ (0≦x≦0.2) and Li_(1+x9)Mn_((2−y9))O₄ (0.05≦x9,y9≦0.15), can be less than about 60° C. For example, during anovercharge tests of these lithium-ion batteries at a voltage greaterthan about 4.2 V, the CID of the invention activated at about between 4kg/cm² and about 10 kg/cm², and the cell skin temperature at that timewas in a range of between about 50° C. and about 60° C. The “183665”prismatic cell has an about 18 mm×36 mm prismatic base and a length ofabout 65 mm, which is about twice the size of the conventional “18650”cell. Thus, the present invention can provide batteries, especiallyrelatively large batteries, having much improved safety, and batterypacks including such batteries.

In addition, the present invention can provide batteries or batterypacks that can be charged at their maximum voltage, e.g., 4.2 V perblock of series of cells, i.e., having their full capacity. Safetyconcerns generally relate to a relatively high temperature associatedwith the exothermic cell chemistry of the Li_(1+x)CoO₂-based systems ata higher charging voltage. With conventional CIDs, which generallyinterrupt the internal current flow of batteries at an internal gaugepressure of about 15 kg/cm², the cell temperature of the batteries maybe excessive before the CIDs activate and interrupt the internal currentflow. If no means of current interrupt exists, cells or batteries mayeventually vent, which can lead to an unsafe situation, because thevented cells or batteries can expel electrolytes which can ignite andcause fire.

The CIDs of the invention, by contrast, can provide a solution to suchproblems, because they cause batteries or battery packs, in which theyare incorporated, to run at their full capacity with lower risk thantypically exists in commercially available embodiments, since theyinterrupt current flow at relatively low temperatures during overcharge.Thus, the batteries and battery packs of the invention can employrelatively large cells, and provide improved capacity with greatersafety by reducing likelihood of thermal runaway in the cells when theyare exposed to abuse conditions, such as an overcharge.

In some embodiments of the invention, the low pressure CID is inelectrical communication with the battery can. This design can provideimproved battery safety particularly in a battery that does not use acrimped cap design. Batteries using crimped cap designs (e.g. steel cancylindrical 18650s found in the market today) often are affected bymanufacturing and safety issues surrounding the can assembly andmaterials, including the facts that such cans use iron-containingmaterials that can corrode over time and that the crimping process isknown to be a possible source of metal contamination in such cells. CIDdevices, used in such conventional batteries, are crimped into thebattery can, and are electrically insulated from the battery can. Whileuse of non-crimped battery designs are known, including use of prismaticAl cans, no CIDs have been developed for use in such cells unlessincorporated by some means of crimping. Additionally, use of crimpingmethods to incorporate CIDs generally is not an efficient utilization ofspace, which is one of a key design consideration for batteries. Incontrast, the present invention enables incorporation of the lowpressure CID in a non-crimped battery can by means other than crimping,partly due to the fact that the CID is in electrical communication withthe battery can. This also enables similar materials to be used in theconstruction of the CID and the can (e.g. Al), and eliminates concernsassociated with iron-containing cans.

In some other embodiments, the present invention employs a CID thatincludes a conical section, such as a frustum-shaped first conductiveplate. The frustum-shaped conductive plate can cause the CID to activateat lower pressures than what is found in similarly sized CID devicesused today that do not employ such a frustum shape. These lowerpressures correlate to improved battery safety, especially with regardto battery safety during an overcharge abuse scenario. In particular, inembodiments where the frustum-shaped first conductive plate has a planarcap sealing an end of the frustum, and the first conductive plate is inelectrical communication with the second conductive plate at the planarcap, the planar cap enables the two plates to be welded to each other.Use of suitable welding technique can enable, at least in part, improvedcontrol of activation pressure of batteries employing CIDs of theinvention, for example, by controlling the position or the number ofwelding. Also, the CID, employing the frustum-shaped conductive plate,can provide the current interrupt function and occupy a significantlyreduced amount of space within the battery, both in terms of overallheight and cross-section, so that more space can be used for materialsdirectly related to power generating aspects of the battery. Inaddition, the invention allows manufacturing of a CID device in anefficient process with consideration to time, cost and quality.Particularly with regards to quality, the frustum-shape enables the CIDdevice of the invention to achieve pressure activation in a narrow rangeand therefore allows better battery design of the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a CID of the invention.

FIGS. 2A-2C show one embodiment of a first conductive plate of the CIDof FIG. 1, wherein FIG. 2A shows a side view of the first conductiveplate, FIG. 2B shows a top view of the first conductive plate, and FIG.2C shows a cross-sectional view of the first conductive plate along lineA-A of FIG. 2B.

FIGS. 3A-3C show one embodiment of a second conductive plate of the CIDof FIG. 1, wherein FIG. 3A shows a plane view of the second conductiveplate, FIG. 3B shows a perspective view of the second conductive plate,and FIG. 3C shows a cross-sectional view of the second conductive platealong line A-A of FIG. 3A.

FIG. 4 show one embodiment of an end plate which can house the CID ofFIG. 1.

FIGS. 5A-5C show one embodiment of a retainer disposed between a portionof a first conductive plate and a portion of a second conductive plate,of the CID of FIG. 1, wherein an insulator component of the retainer isshown in FIG. 5A, a side view of a ring component of the retainer isshown in FIG. 5B, and a top view of the ring of the retainer is shown inFIG. 5C.

FIGS. 6A and 6B show one embodiment of the CID of the invention, whereinFIG. 6A shows an assembly of a first conductive plate, a secondconductive plate and a retainer between them onto an end plate, and FIG.6B shows the assembled CID.

FIGS. 7A and 7B show another embodiment of the CID of the invention,wherein FIG. 7A shows an assembly of a first conductive plate, a secondconductive plate and a retainer between them onto an end plate, and FIG.7B shows the assembled CID.

FIG. 8A shows one embodiment in a prismatic format of the battery of theinvention.

FIG. 8B shows a bottom view of a lid portion of the battery of FIG. 8A,taken from the inside of the battery.

FIG. 8C shows a cross sectional view of the lid portion of FIG. 8B alongthe line A-A.

FIG. 8D shows one embodiment of a cylindrical format of the battery ofthe invention.

FIG. 8E shows a side view of the bottom can portion of the battery ofFIG. 8D from inside of the battery.

FIG. 8F shows a side view of the top lid portion of the battery of FIG.8E from inside of the battery.

FIG. 9 is a schematic circuitry showing how individual cells in theinvention are preferably connected when arranged together in a batterypack of the invention.

FIG. 10 is a graph showing CID trip pressures of the CIDs of theinvention.

FIG. 11 is a graph showing pressure rise rates with respect toovercharging voltages of the batteries of the invention, when thebatteries were overcharged at a 2C rate per minute.

FIG. 12 is a graph showing cell skin temperatures of the batteries ofthe invention measured when their CIDs were activated.

FIG. 13 is a graph showing the maximum cell skin temperatures ofbatteries of the invention that were overcharged at a 2C rate perminute.

FIG. 14 is a graph showing calculated pressures versus the measured cellskin temperatures of a battery of the invention that was overcharged ata 2C rate per minute.

FIG. 15 is a graph showing cell skin temperatures of the batteries ofthe invention with CIDs of the invention (curves A and B) and controlbatteries with conventional CIDs (curves C and D).

DETAILED DESCRIPTION OF THE INVENTION

The foregoing will be apparent from the following more particulardescription of example embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingembodiments of the present invention.

As used herein, the “terminals” of the batteries of the invention meanthe parts or surfaces of the batteries to which external electriccircuits are connected.

The batteries of the invention typically include a first terminal inelectrical communication with a first electrode, and a second terminalin electrical communication with a second electrode. The first andsecond electrodes are contained within the cell casing of a battery ofthe invention, for example, in a “jelly roll” form. The first terminalcan be either a positive terminal in electrical communication with apositive electrode of the battery, or a negative terminal in electricalcommunication with a negative electrode of the battery, and vice versafor the second terminal. Preferably, the first terminal is a negativeterminal in electrical communication with a negative electrode of thebattery, and the second terminal is a positive terminal in electricalcommunication with a positive electrode of the battery.

As used herein, the phrase “electrically connected” or “in electricalcommunication” or “electrically contacted” means certain parts are incommunication with each other by flow of electrons through conductors,as opposed to electrochemical communication which involves flow of ions,such as Li⁺, through electrolytes.

The CID of the battery of the invention can active at an internal gaugepressure in a range of, for example, between about 4 kg/cm² and about 10kg/cm², such as between about 4 kg/cm² and about 9 kg/cm², between about5 kg/cm² and about 9 kg/cm² or 7 kg/cm² and about 9 kg/cm². As usedherein, “activation” of the CID means that current flow of an electronicdevice through the CID is interrupted. In a specific embodiment, the CIDof the invention includes a first conductive plate and a secondconductive plate in electrical communication with each other (e.g., bywelding, crimping, riveting, etc.). In this CID, “activation” of the CIDmeans that the electrical communication between the first and secondconductive plates is interrupted. Preferably, when the second conductiveplate separates from (e.g., deforms away or is detached from) the firstconductive plate, no rupture occurs in the first conductive plate.

In some embodiments, the CID of the battery of the invention, whichemploys a first conductive plate and a second conductive plate that isin electrical communication with, and pressure (i.e., fluid such as gas)communication with, the first conductive plate and with the battery canof the battery, activates at an internal gauge pressure in a range of,for example, between about 4 kg/cm² and about 9 kg/cm², such as betweenabout 5 kg/cm² and about 9 kg/cm² or 7 kg/cm² and about 9 kg/cm². Inthese embodiments, preferably, the first conductive plate includes acone- or dome-shaped part. More preferably, at least a portion of thetop (or cap) of the cone- or dome-shaped part is essentially planar.Preferably, the first and second conductive plates are in direct contactwith each other at a portion of the essentially planar cap. Morepreferably, the first conductive plate includes a frustum having anessentially planar cap.

FIG. 1 shows one specific embodiment of the CID of the invention. CID 10shown in FIG. 1 includes first conductive plate 12 and second conductiveplate 24. As shown in FIGS. 2A-2C, first conductive plate 12 includesfrustum 14 that includes first end 16 and second end 18. First end 16has a broader diameter than second end 18. First conductive plate 12also includes base 20 extending radially from a perimeter of first end16 of frustum 14. Essentially planar cap 22 seals second end 18 offrustum 14. As used herein, the term “frustum” means the basal wall part(excluding the bottom and top ends) of a solid right circular cone(i.e., solid generated by rotating a right triangle about one of itslegs) by cutting off the top intersected between two parallel planes.

As used herein, the term “essentially planar cap” means a planar capwhich includes a surface that sufficiently resembles a plane topotentially contact a planar surface randomly at more than one point andwhereby the planar cap and the planar surface can be fused by a suitablemeans, such as by spot welding. In some embodiments, deformation of theessentially planar cap caused by assembly or by fabrication of the firstconductive plate having the essentially planar cap to form CID 10 (e.g.,by welding of first conductive plate 12 to second conductive plate 24)is considered to be essentially planar.

Preferably, flat cap 22 and/or base 20 has a thickness (indicated withreference character “d” in FIG. 2C) in a range of between about 0.05millimeters and about 0.5 millimeters, such as between about 0.05millimeters and about 0.3 millimeters, between about 0.05 millimetersand 0.2 millimeters, between about 0.05 millimeters and about 0.15millimeters (e.g., about 0.127 millimeter (or about 5 milli-inch)).

Preferably, the diameter of flat cap 22 (indicated with referencecharacter “b” in FIG. 2C) is in a range of between about 2 millimetersand about 10 millimeters, more preferably between 5 millimeters andabout 10 millimeters, even more preferably between about 5 millimetersand 8 millimeters (e.g., between about 0.20 inches and 0.25 inches),such as about 5.5 millimeter (or about 0.215 inch).

Preferably, the height of essentially planar cap 22 from base 20(indicated with reference character “c” in FIG. 2C) is in a range ofbetween about 0.5 millimeter and about 1 millimeter, more preferablybetween about 0.6 millimeter and about 0.8 millimeter, such as about0.762 millimeter (or about 0.315 inch).

Preferably, frustum 14 has an angle relative to a plane parallel to base20 in a range of between about 15 degrees and about 25 degrees, such asbetween about 18 degrees and about 23 degrees, or between about 19degrees and about 21 degrees. More preferably, frustum 14 has an angleof about 21 degrees relative to a plane parallel to base 20. Preferably,frustum 14 has a diameter ratio of first end 16 to second end 18 (i.e.,ratio of “b” to “a” in FIG. 2C) in a range of between about 1:1.20 andabout 1:1.35, such as between about 1:1.23 and about 1:1.28.

Second conductive plate 24 is in electrical and pressure (i.e., fluidsuch as gas) communication with first conductive plate 12. Preferably,second conductive plate 24 defines at least one opening 26 through whichfirst conductive plate 12 and second conductive plate 24 are in pressurecommunication with each other. One embodiment of such second conductiveplate 24 is shown in FIGS. 3A-3C. As shown in FIGS. 3A and 3B, secondconductive plate 24 defines at least one opening 26 through which firstconductive plate 12 and second conductive plate 24 are in pressure(e.g., gas) communication with each other. Preferably, second conductiveplate 24 includes embossment (or depression) 28, and, thus, has flatside 30 and depression side 32 (FIG. 3C). Referring back to FIG. 1, flatside 30 of second conductive plate 24 faces toward first conductiveplate 12. Second conductive plate 24 is in electrical contact withessentially planar cap 22 of first conductive plate 12, preferablythrough a weld. Preferably, the weld connecting essentially planar cap22 of first conductive plate 12 and second conductive plate 24 is atflat side 30 at depression 28. Preferably, the weld is at least one spotweld, such as one, two, three or four. More preferably, at least one ofthe spot welds includes aluminum. Even more preferably, the weld is twospot welds. Preferably, the two spot welds are separated from eachother.

Any suitable welding technique known in the art can be used to weldfirst and second conductive plates 12 and 24. Preferably, a laserwelding technique is employed in the invention. More preferably, duringthe welding process (e.g., laser welding process), a temperature offirst conductive plate 12 is controlled so as not to exceed the meltingpoint of a surface of the first conductive plate opposite the weld. Suchcontrolling can be done using any suitable cooling methods known in theart. Preferably, the thickness of second conductive plate 24 proximateto the weld with first conductive plate 12 is equal to or greater thanone-half of the thickness of first conductive plate 12 proximate to theweld, but less than the thickness of the first conductive plateproximate to the weld.

Referring back to FIG. 1, CID 10 optionally includes end plate 34. Oneparticular embodiment of end plate 34 is shown in FIG. 4. End plate 34includes first recess 36 and second recess 38. The diameter of firstrecess 36 (indicated with reference character “a” in FIG. 4) ispreferably co-terminus with the outer diameter of base 20 of firstconductive plate 12 (as shown in FIG. 1). As used herein, the“co-terminus” means that the diameter of first recess 36 is essentiallythe same as, or slightly larger than the outer diameter of base 20 offirst conductive plate 12 by between about 101% and about 120% (e.g.,about 110%). The depth of first recess 36 (indicated with referencecharacter “b” in FIG. 4) is slightly less, for example, about 90% less,than the thickness of base 20 of first conductive plate 12 (indicatedwith reference character “d” in FIG. 2C). Second recess 38 canaccommodate frustum 14 of first conductive plate 12 upon its reversal.This second recess 38 is preferably co-terminus with the perimeter offirst end 16 of frustum 14 of first conductive plate 12 (as shown inFIG. 1). As used herein, the “co-terminus” means that the diameter(indicated with reference character “c” in FIG. 4) of second recess 38is essentially the same as, or slightly larger than that of cap 22 offrustum 14, by between about 101% and about 120% (e.g., about 103%). Thedepth of second recess 38 (indicated with reference character “d” inFIG. 4), as measured from first recess 36, is slightly larger, forexample, between about 110% and about 130% (e.g., about 125%) larger,than the height of first conductive plate 12 (indicated with referencecharacter “c” in FIG. 2C).

As shown in FIG. 1, first conductive plate 12 and end plate 34 are inelectrical contact with each other. This electrical contact can be madeby any suitable method known in the art, for example, by welding,crimping, riveting, etc. Preferably, first conductive plate 12 and endplate 34 are welded to each other. Any suitable welding technique knownin the art can be used. Preferably, first conductive plate 12 and endplate 34 are hermetically joined. Preferably, a laser welding techniquesis employed in the invention. More preferably, a circumferential laserwelding technique is used to hermetically join first conductive plate 12and end plate 34, for example, either by means of seam welding at thecircumferential interface between the two parts or by means ofpenetration welding at base 20 of first conductive plate 12. Preferably,the welding is circumferentially placed around the middle of base 20 orthe edge of base 20 (indicated with reference characters “a” and “b,”respectively, in FIG. 1). Preferably, during the welding process (e.g.,laser welding process), a temperature of first conductive plate 12 iscontrolled so as not to exceed the melting point of a surface of thefirst conductive plate opposite the weld. Such temperature control canbe obtained using any suitable cooling method known in the art.

First conductive plate 12, second conductive plate 24 and end plate 34can be made of any suitable conductive material known in the art for abattery. Examples of suitable materials include aluminum, nickel andcopper, preferably aluminum, such as Aluminum 3003 series (e.g.,Aluminum 3003H-14 series for second conductive plate 24 and end plate34, and Aluminum 3003H-0 series for first conductive plate 12).Preferably, first conductive plate 12 and second conductive plate 24 aremade of substantially the same metals. More preferably, first conductiveplate 12, second conductive plate 24 and end plate 36 are made ofsubstantially the same metals. As used herein, the term “substantiallysame metals” means metals that have substantially the same chemical andelectrochemical stability at a given voltage, e.g., the operationvoltage of a battery. In one specific embodiment, at least one of firstconductive plate 12 and second conductive plate 24 includes aluminum,such as Aluminum 3003 series. In one more specific embodiment, firstconductive plate 12 includes aluminum which is softer than that ofsecond conductive plate. Preferably, first conductive plate 12 andsecond conductive plate 24 both include aluminum. Even more preferably,first conductive plate 12, second conductive plate 24 and end plate 36all include aluminum, such as Aluminum 3003 series.

Frustum 14 and flat cap 22 of first conductive plate 12, embossment 28of second conductive plate 24 and recesses 36 and 38 of end plate 34 canbe made by any suitable method known in the art, for example, bystamping, coining, and/or milling techniques.

Referring back to FIG. 1, in a preferred embodiment, the CID of theinvention further includes retainer 40 (e.g., electrically insulatinglayer, ring or gasket) between a portion of first conductive plate 12and a portion of second conductive plate 24. Retainer 40, such as anelectrically insulating ring, extends about the perimeter of frustum 14,and between base 20 of first conductive plate 12 and second conductiveplate 24.

One specific embodiment of retainer 40 is shown in FIGS. 5A-5C, andFIGS. 6A and 6B. Retainer 40 of FIGS. 5A-5C, and FIGS. 6A and 6Bincludes an insulator 42, such as an electrically insulating ring, whichdefines at least two grooves 43, 45 about a perimeter of the insulator42. Retainer 40 further includes ring 44, such as a metal ring, havingtabs 46. As shown in FIGS. 6A and 6B, ring 44 can rest inside groove 45and second conductive plate 24 can rest inside groove 43. Tabs 46 can bemalleably adjusted and secured to a metal surface of lid 106 (or asurface of an end plate which is a part of the lid), on which firstconductive plate 12 is resting, thereby securing ring 44 over firstconductive plate 12. As shown in FIGS. 5A and 5B, and 6A and 6B, thenumber of tabs 46 can be any number, for example, one, two, three orfour.

Another specific embodiment of retainer 40 is shown in FIGS. 7A and 7B.Retainer 40 of FIGS. 7A and 7B is an insulator, such as an electricallyinsulating ring, that defines at least one opening 48 and groove 50about a perimeter of retainer 40. As shown in FIG. 7A, second conductiveplate 24 can rest inside groove 50. In this embodiment, first conductiveplate 12 preferably includes at least one tab 52. Tabs 52 of firstconductive plate 12, and opening 48 of retainer 40 are capable ofalignment when retainer 40 and base 22 of first conductive plate 12 areconcentric. Tabs 52 of first conductive plate 12 can be malleablyadjusted to secure retainer 40 to first conductive plate 12, as shown inFIG. 7B.

The CIDs of the invention, such as CID 10, can be included in a battery,such as a lithium-ion battery. FIGS. 8A and 8D show two differentembodiments of battery 100 (which is collectively referred to forbattery 100A of FIG. 8A and battery 100B of FIG. 8D) of the battery ofthe invention. FIG. 8B shows a bottom view of a lid portion of battery100, including CID 10, when it is seen from the inside of the battery.FIGS. 8C and 8F show a cross-sectional view of the lid portion, ofbattery 100A of FIG. 8A and, of battery 100B of FIG. 8D, respectively.

As shown in FIGS. 8A-8F, battery 100 includes CID 10, battery can 102that includes cell casing 104 and lid 106, first electrode 108 andsecond electrode 110. First electrode 108 is in electrical communicationwith a first terminal of the battery, and second electrode 110 is inelectrical communication with a second terminal of the battery. The cellcasing 104 and lid 106 are in electrical contact with each other. Thetabs (not shown in FIG. 8A and FIG. 8D) of first electrode 108 areelectrically connected (e.g., by welding, crimping, riveting, etc.) toelectrically-conductive, first component 116 of feed-through device 114.The tabs (not shown in FIG. 8A and FIG. 8D) of second electrode 110 arein electrically connected (e.g., by welding, crimping, riveting, etc.)to second conductive plate 24 of CID 10.

Features of CID 10, including preferred features, are as describedabove. Specifically, in FIGS. 8A-8C and FIGS. 8D-8F, CID 10 includesfirst conductive plate 12, second conductive plate 24, end plate 34 andretainer 40. As shown in FIG. 8A and FIG. 8D, in battery 100, end plate34 is a part of lid 106 of cell can 102. Although not shown, separateend plate 34 can be used in the invention. Features, including preferredfeatures, of first conductive plate 12, second conductive plate 24,retainer 40 and end plate 34 are as described above. Preferably, whensecond conductive plate 24 separates from first conductive plate 12, norupture occurs in second conductive plate 24 so that gas inside battery100 does not go out through second conductive plate 24. The gas can exitbattery 100 through one or more venting means 112 (see FIG. 8A and FIG.8D) at cell casing 104, which will be discussed later in detail, whenthe pressure keeps increasing and reaches a predetermined value foractivation of venting means 112. In some embodiments, the predeterminedvalue for activation of venting means 112, which is, for example, aninternal gauge pressure in a range of between about 10 kg/cm² and about20 kg/cm², such as between about 12 kg/cm² and about 20 kg/cm², ishigher than that for the activation of CID 10, for example, betweenabout 4 kg/cm² and about 10 kg/cm² or between about 4 kg/cm² and about 9kg/cm². This feature helps prevent premature gas leakage, which candamage neighboring batteries (or cells) which are operating normally.So, when one of a plurality of cells in the battery packs of theinvention is damaged, the other healthy cells are not damaged. It isnoted that gauge pressure values or sub-ranges suitable for theactivation of CID 10 and those for activation of venting means 112 areselected from among the predetermined gauge pressure ranges such thatthere is no overlap between the selected pressure values or sub-ranges.Preferably, the values or ranges of gauge pressure for the activation ofCID 10 and those for the activation of venting means 112 differ by atleast about 2 kg/cm², more preferably by at least about 4 kg/cm², evenmore preferably by at least about 6 kg/cm², such as by about 7 kg/cm².

CID 10 can be made as described above. Attachment of CID 10 to batterycan 102 of battery 100 can be done by any suitable means known in theart. Preferably, CID 10 is attached to battery can 102 via welding, andmore preferably by welding first conductive plate 12 onto end plate 34of lid 106, as described above for the CID of the invention.

Although one CID 10 is employed in battery 100, more than one CID 10 canbe employed in the invention. Also, although in FIGS. 8A-8C and FIGS.8D-8F, CID 10 in electrical contact with second electrode 110 isdepicted, in some other embodiments, CID 10 can be in electricalcommunication with first electrode 108 and feed-through device 114 thatis insulated from cell can 102, and second electrode 110 is directly inelectrical contact with cell can 102. In such embodiments, CID 10 is notin electrical communication with cell can 102. Also, although in FIGS.8A-8C and FIGS. 8E-8F, CID 10 is depicted to be positioned at inside 105of lid 106 (see FIG. 8C and FIG. 8F), CID 10 of the invention can beplaced at any suitable place of battery 100, for example, on the side ofcell casing 102 or top side 107 of lid 106.

As shown in FIG. 8C and FIG. 8E, feed-through device 114 includes firstconductive component 116, which is electrically conductive, insulator118, and second conductive component 120, which can be the firstterminal of battery 100. As used herein, the term “feed-through”includes any material or device that connects an electrode of a batterywithin a space defined by a casing and lid of a battery, with acomponent of the battery external to that defined internal space.Preferably, the feed-through material or device extends through apass-through hole defined by a lid of the battery. Feed-through device114 can pass through a lid of a cell casing of a battery withoutdeformation, such as by bending, twisting and/or folding of electrodetabs, and, thus, can increase cell capacity. Such a feed-through devicecan potentially increase (e.g., 5-15%) cell capacity due to increasedvolume utilization, as compared to that of a conventional lithiumbattery in which current-carrying tabs are folded or bent into a cellcasing and are welded with internal electrodes. First and secondconductive components, 116, 120, can be made of any suitableelectrically conductive material, such as nickel. Any suitableinsulating materials known in the art can be used for insulator 118.

Cell casing 104 can be made of any suitable conductive material which isessentially stable electrically and chemically at a given voltage ofbatteries, such as the lithium-ion batteries of the invention. Examplesof suitable materials of cell casing 104 include aluminum, nickel,copper, steel, nickel-plated iron, stainless steel and combinationsthereof. Preferably, cell casing 104 is of, or includes, aluminum.Examples of suitable materials of lid 106 are the same as those listedfor cell casing 104. Preferably lid 106 is made of the same material ascell casing 104. In a more preferred embodiment, both cell casing 104and lid 106 are formed of, or include, aluminum. Lid 106 canhermetically seal cell casing 104 by any suitable method known in theart (e.g., welding, crimping, etc). Preferably, lid 106 and cell casing104 are welded to each other. Preferably, the weld connecting lid 106and cell casing 104 ruptures when an gauge pressure between lid 106 andcell casing 104 is greater than about 20 kg/cm².

In a preferred embodiment of the battery of the invention, at least oneof cell casing 104 and lid 106 of battery can 102 are in electricalcommunication with second electrode 110 of battery 100 through CID 108,as shown in FIG. 8A and FIG. 8D. Battery can 102 is electricallyinsulated from first terminal 120, and at least a portion of cell can102 is at least a component of a second terminal of battery 100, or iselectrically connected to the second terminal. In a more preferredembodiment, at least a portion of lid 106 or the bottom end of cellcasing 104, serves as the second terminal.

As shown in FIG. 8C and FIG. 8F, at least a portion of battery can 102,e.g., lid 106 or the bottom end of cell casing 104, can be the secondterminal of battery 100. Alternatively, at least a portion of batterycan 102 can be at least a component of the second terminal, orelectrically connected to the second terminal. Lid 106 of cell can 102is electrically insulated from feed-through device 114 by insulator 118,such as an insulating gasket or ring. The insulator is formed of asuitable insulating material, such as polypropylene, polyvinylfluoride(PVF), natural polypropylene, etc. Preferably, the first terminal is anegative terminal, and the second terminal of battery 100, which is inelectrical communication with cell can 102, is a positive terminal.

Referring back to FIG. 8A and FIG. 8D, in some preferred embodiments,cell casing 104 includes at least one venting means 112 as a means forventing interior gaseous species when necessary, such as when gas withinlithium ion battery 100 is greater than a value, for example, aninternal gauge pressure in a range of between about 10 kg/cm² and about20 kg/cm², such as between about 12 kg/cm² and about 20 kg/cm² orbetween about 10 kg/cm² and about 18 kg/cm². It is to be understood thatany suitable type of venting means can be employed as long as the meansprovide hermetic sealing in normal battery operation conditions. Varioussuitable examples of venting means are described in U.S. ProvisionalApplication No. 60/717,898, filed on Sep. 16, 2005, the entire teachingsof which are incorporated herein by reference.

Specific examples of venting means include vent scores. As used herein,the term “score” means partial incision of section(s) of a cell casing,such as cell casing 104, that is designed to allow the cell pressure andany internal cell components to be released at a defined internalpressure. Preferably, venting means 112 is a vent score, morepreferably, vent score that is directionally positioned away from auser/or neighboring cells. More than one vent score can be employed inthe invention. In some embodiments, patterned vent scores can beemployed. The vent scores can be parallel, perpendicular, diagonal to amajor stretching (or drawing) direction of the cell casing materialduring creation of the shape of the cell casing. Consideration is alsogiven to vent score properties, such as depth, shape and length (size).

The batteries of the invention can further include a positive thermalcoefficient layer (PTC) in electrical communication with either thefirst terminal or the second terminal, preferably in electricalcommunication with the first terminal. Suitable PTC materials are thoseknown in the art. Generally, suitable PTC materials are those that, whenexposed to an electrical current in excess of a design threshold, itselectrical conductivity decreases with increasing temperature by severalorders of magnitude (e.g., 10⁴ to 10⁶ or more). Once the electricalcurrent is reduced below a suitable threshold, in general, the PTCmaterial substantially returns to the initial electrical resistivity. Inone suitable embodiment, the PTC material includes small quantities ofsemiconductor material in a polycrystalline ceramic, or a slice ofplastic or polymer with carbon grains embedded in it. When thetemperature of the PTC material reaches a critical point, thesemiconductor material or the plastic or polymer with embedded carbongrains forms a barrier to the flow of electricity and causes electricalresistance to increase precipitously. The temperature at whichelectrical resistivity precipitously increases can be varied byadjusting the composition of the PTC material, as is known in the art.An “operating temperature” of the PTC material is a temperature at whichthe PTC exhibits an electrical resistivity about half way between itshighest and lowest electrical resistance. Preferably, the operatingtemperature of the PTC layer employed in the invention is between about70° Celsius and about 150° Celsius.

Examples of specific PTC materials include polycrystalline ceramicscontaining small quantities of barium titanate (BaTiO₃), and polyolefinsincluding carbon grains embedded therein. Examples of commerciallyavailable PTC laminates that include a PTC layer sandwiched between twoconducting metal layers include LTP and LR4 series manufactured byRaychem Co. Generally, the PTC layer has a thickness in a range of about50 μm and about 300 μm.

Preferably, the PTC layer includes electrically conductive surface, thetotal area of which is at least about 25% or at least about 50% (e.g.,about 48% or about 56%) of the total surface area of lid 106 or thebottom of battery 100. The total surface area of the electricallyconductive surface of the PTC layer can be at least about 56% of thetotal surface area of lid 106 or the bottom of battery 100. Up to 100%of the total surface area of lid 106 of battery 100 can be occupied bythe electrically conductive surface of the PTC layer. Alternatively, thewhole, or part, of the bottom of battery 100 can be occupied by theelectrically conductive surface of the PTC layer.

The PTC layer can be positioned externally to the battery can, forexample, over a lid of the battery can.

In a preferred embodiment, the PTC layer is between a first conductivelayer and a second conductive layer and at least a portion of the secondconductive layer is at least a component of the first terminal, or iselectrically connected to the first terminal. In a more preferredembodiment, the first conductive layer is connected to the feed-throughdevice. Suitable examples of such a PTC layer sandwiched between thefirst and second conductive layers are described in U.S. patentapplication Ser. No. 11/474,081, filed on Jun. 23, 2006, the entireteachings of which are incorporated herein by reference.

In a preferred embodiment, the battery of the invention includes batterycan 102 that includes cell casing 104 and lid 106, at least one CID,preferably CID 10 as described above, in electrical communication witheither of the first or second electrodes of the battery, and at leastone venting means 112 on cell casing 104. As described above, batterycan 102 is electrically insulated from the first terminal that is inelectrical communication with the first electrode of the battery. Atleast a portion of battery can 102 is at least a component of the secondterminal that is in electrical communication with the second electrodeof the battery. Lid 106 is welded on cell casing 104 such that thewelded lid is detached from cell casing 104 at an internal gaugepressure greater than about 20 kg/cm². The CID includes a firstconductive plate (e.g., first conductive plate 12) and a secondconductive plate (e.g., second conductive plate 24) in electricalcommunication with each other, preferably by a weld. This electricalcommunication is interrupted at an internal gauge pressure between about4 kg/cm² and about 9 kg/cm², between about 5 kg/cm² and about 9 kg/cm²or between about 7 kg/cm² and about 9 kg/cm². For example, the first andsecond conductive plates are welded, e.g., laser welded, to each othersuch that the weld ruptures at the predetermined gauge pressure. Atleast one venting means 112 is formed to vent interior gaseous specieswhen an internal gauge pressure in a range of between about 10 kg/cm²and about 20 kg/cm² or between about 12 kg/cm² and about 20 kg/cm². Asdescribed above, it is noted that gauge pressure values or sub-rangessuitable for the activation of CID 10 and those for activation ofventing means 112 are selected from among the predetermined gaugepressure ranges such that there is no overlap between the selectedpressure values or sub-ranges. Preferably, the values or ranges of gaugepressure for the activation of CID 10 and those for the activation ofventing means 112 differ by at least about 2 kg/cm² pressure difference,more preferably by at least about 4 kg/cm², even more preferably by atleast about 6 kg/cm², such as by about 7 kg/cm². Also, it is noted thatgauge pressure values or sub-ranges suitable for the rupture of thewelded lid 106 from cell casing 104 and those for activation of ventingmeans 112 are selected from among the predetermined gauge pressureranges such that there is no overlap between the selected pressurevalues or sub-ranges. Preferably, the values or ranges of gauge pressurefor the activation of CID 10 and those for the activation of ventingmeans 112 differ by at least about 2 kg/cm² pressure difference, morepreferably by at least about 4 kg/cm², even more preferably by at leastabout 6 kg/cm².

Preferably, the battery of the invention is rechargeable, such as arechargeable lithium-ion battery.

Preferably, the battery of the invention, such as a lithium-ion battery,has an internal gauge pressure of less than or equal to about 2 kg/cm²under a normal working condition. For such a battery of the invention,in one embodiment, the active electrode materials are first activatedand then the battery can of the battery is hermetically sealed.

The battery (or cell) of the invention can be cylindrical (e.g., 26650,18650, or 14500 configuration) or prismatic (stacked or wound, e.g.,183665 or 103450 configuration). Preferably, they are prismatic, and,more preferably, of a prismatic shape that is oblong. Although thepresent invention can use all types of prismatic cell casings, an oblongcell casing is preferred partly due to the two features described below.

The available internal volume of an oblong shape, such as the 183665form factor, is larger than the volume of two 18650 cells, whencomparing stacks of the same external volume. When assembled into abattery pack, the oblong cell fully utilizes more of the space that isoccupied by the battery pack. This enables novel design changes to theinternal cell components that can increase key performance featureswithout sacrificing cell capacity relative to that found in the industrytoday. Due to the larger available volume, one can elect to use thinnerelectrodes, which have relatively higher cycle life and a higher ratecapability. Furthermore, an oblong can has larger flexibility. Forinstance, an oblong shape can flex more at the waist point compared to acylindrically shaped can, which allows less flexibility as stackpressure increases upon charging. The increased flexibility decreasesmechanical fatigue on the electrodes, which, in turn, causes highercycle life. Also, clogging of pores of a separator in batteries can beimproved by a relatively low stack pressure.

A particularly desired feature, allowing relatively higher safety, isavailable for the oblong shaped battery compared to the prismaticbattery. The oblong shape provides a snug fit to the jelly roll, whichminimizes the amount of electrolyte necessary for the battery. Therelatively low amount of electrolyte results in less available reactivematerial during a misuse scenario and hence higher safety. In addition,cost is lower due to a lower amount of electrolyte. In the case of aprismatic can with a stacked electrode structure, whose cross-section isin a rectangular shape, essentially full volume utilization is possiblewithout unnecessary electrolyte, but this type of can design is moredifficult and hence more costly from a manufacturing point-of-view.

Referring to FIG. 9, in some embodiments of the invention, a pluralityof lithium-ion batteries of the invention (e.g., 2 to 5 cells) can beconnected in a battery pack, wherein each of the batteries (cells) isconnected with each other in series, parallel, or in series andparallel. In some battery packs of the invention, there are no parallelconnections between the batteries.

Preferably, at least one cell has a prismatic shaped cell casing, andmore preferably, an oblong shaped cell casing, as shown in FIG. 8A.Preferably, the capacity of the cells in the battery pack is typicallyequal to or greater than about 3.0 Ah, more preferably equal to orgreater than about 4.0 Ah. The internal impedance of the cells ispreferably less than about 50 milli-ohms, and more preferably less than30 milli-ohms.

The lithium-ion batteries and battery packs of the invention can be usedfor portable power devices, such as portable computers, power tools,toys, portable phones, camcorders, PDAs and the like. In portableelectronic devices using lithium-ion batteries, their charges are, ingeneral, designed for a 4.20 V charging voltage. Thus, the lithium-ionbatteries and battery packs of the invention are particularly useful forthese portable electronic devices.

The present invention also includes methods of producing a battery, suchas a lithium-ion battery, as described above. The methods includeforming a cell casing as described above, and disposing a firstelectrode and a second electrode within the cell casing. A currentinterrupt device, as described above (e.g., current interrupt device28), is formed and electrically connected with the cell casing.

Positive and negative electrodes and electrolytes for the lithium-ionbatteries of the invention can be formed by suitable methods known inthe art.

Examples of suitable negative-active materials for the negativeelectrodes include any material allowing lithium to be doped or undopedin or from the material. Examples of such materials include carbonaceousmaterials, for example, non-graphitic carbon, artificial carbon,artificial graphite, natural graphite, pyrolytic carbons, cokes such aspitch coke, needle coke, petroleum coke, graphite, vitreous carbons, ora heat-treated organic polymer compounds obtained by carbonizing phenolresins, furan resins, or similar, carbon fibers, and activated carbon.Further, metallic lithium, lithium alloys, and an alloy or compoundthereof are usable as the negative active materials. In particular, themetal element or semiconductor element allowed to form an alloy orcompound with lithium may be a group IV metal element or semiconductorelement, such as, but not limited to, silicon or tin. In particular,amorphous tin that is doped with a transition metal, such as cobalt oriron/nickel, is a metal that is suitable as an anode material in thesetypes of batteries. Oxides allowing lithium to be doped or undoped in orout from the oxide at a relatively basic potential, such as iron oxide,ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide, andtin oxide, and nitrides, similarly, are usable as the negative-activematerials.

Suitable positive-active materials for the positive electrodes includeany material known in the art, for example, lithium nickelate (e.g.,Li_(1+x)NiM′O₂ where x is equal to or greater than zero and equal to orless than 0.2), lithium cobaltate (e.g., Li_(1+x)CoO₂ where x is equalto or greater than zero and equal to or less than 0.2), olivine-typecompounds (e.g., Li_(1+x)FePO₄ where x is equal to or greater than zeroand equal to or less than 0.2), manganate spinel (e.g.,Li_(3+x9)Mn_(2−y9)O₄ (x9 and y9 are each independently equal to orgreater than zero and equal to or less than 0.3, e.g., 0≦x9, y9≦0.2 or0.05≦x9, y9≦0.15) or Li_(1+x1)(Mn_(1−x1)(Mn_(1−y1)A′_(y2))_(2−x2)O_(z1))(x1 and x2 are each independently equal to or greater than 0.01 andequal to or less than 0.3; y1 and y2 are each independently equal to orgreater than 0.0 and equal to or less than 0.3; z1 is equal to orgreater than 3.9 and equal to or less than 4.2), and mixtures thereof.Various examples of suitable positive-active materials can be found ininternational application No. PCT/US2005/047383, filed on Dec. 23, 2005,U.S. patent application Ser. No. 11/485,068, file on Jul. 12, 2006, andInternational Application, filed on Jun. 22, 2007 under Attorney'sDocket No. 3853.1001-015, entitled “Lithium-Ion Secondary Battery”, theentire teachings of all of which are incorporated herein by reference.

In one specific embodiment, the positive-active materials for thepositive electrodes of the invention include a lithium cobaltate, suchas Li_((1+x8))CoO_(z8). More specifically, a mixture of about 60-90 wt %(e.g. about 80 wt %) of a lithium cobaltate, such as Li_((1+x8)CoO)_(z8), and about 40-10 wt % (e.g., about 20 wt %) of a manganate spinel,such as Li_((1+x1))Mn₂O_(z1), preferably Li_((1+x1))Mn₂O₄, is employedfor the invention. The value x1 is equal to or greater than zero andequal to or less than 0.3 (e.g., 0.05≦x1≦0.2 or 0.05≦x1≦0.15). The valuez1 is equal to or greater than 3.9 and equal to or greater than 4.2. Thevalue x8 is equal to or greater than zero and equal to or less than 0.2.The value z8 is equal to or greater than 1.9 and equal to or greaterthan 2.1.

In another specific embodiment, the positive-active materials for theinvention include a mixture that includes a lithium cobaltate, such asLi_((1+x8))CoO_(z8), and a manganate spinel represented by an empiricalformula of Li_((1+x1))(Mn_(1−y1)A′_(y2))_(2−x2)O_(z1). The values x1 andx2 are each independently equal to or greater than 0.01 and equal to orless than 0.3. The values y1 and y2 are each independently equal to orgreater than 0.0 and equal to or less than 0.3. The value z1 is equal toor greater than 3.9 and equal to or less than 4.2. A′ is at least onemember of the group consisting of magnesium, aluminum, cobalt, nickeland chromium. More specifically, the lithium cobaltate and the manganatespinel are in a weight ratio of lithium cobaltate: manganate spinelbetween about 0.95:0.05 and about 0.9:0.1 to about 0.6:0.4.

In yet another specific embodiment, the positive-active materials forthe invention include a mixture that includes 100% of a lithiumcobaltate, such as Li_((1+x8))CoO_(z8).

In yet another specific embodiment, the positive-active materials forthe invention include at least one lithium oxide selected from the groupconsisting of: a) a lithium cobaltate; b) a lithium nickelate; c) amanganate spinel represented by an empirical formula ofLi_((1+x1))(Mn_(1−y1)A′_(y2))_(2−x2)O_(z1); d) a manganate spinelrepresented by an empirical formula of Li_((1+x1))Mn₂O_(z1) orLi_(1+x9)Mn_(2−y9)O₄; and e) an olivine compound represented by anempirical formula of Li_((1−x10))A″_(x10)MPO₄. The values of x1, z1, x9and y9 are as described above. The value, x2, is equal to or greaterthan 0.01 and equal to or less than 0.3. The values of y1 and y2 areeach independently equal to or greater than 0.0 and equal to or lessthan 0.3. A′ is at least one member of the group consisting ofmagnesium, aluminum, cobalt, nickel and chromium. The value, x10, isequal to or greater than 0.05 and equal to or less than 0.2, or thevalue, x10, is equal to or greater than 0.0 and equal to or less than0.1. M is at least one member of the group consisting of iron,manganese, cobalt and magnesium. A″ is at least one member of the groupconsisting of sodium, magnesium, calcium, potassium, nickel and niobium.

A lithium nickelate that can be used in the invention includes at leastone modifier of either the Li atom or Ni atom, or both. As used herein,a “modifier” means a substituent atom that occupies a site of the Liatom or Ni atom, or both, in a crystal structure of LiNiO₂. In oneembodiment, the lithium nickelate includes only a modifier of, orsubstituent for, Li atoms (“Li modifier”). In another embodiment, thelithium nickelate includes only a modifier of, or substituent for, Niatoms (“Ni modifier”). In yet another embodiment, the lithium nickelateincludes both the Li and Ni modifiers. Examples of Li modifiers includebarium (Ba), magnesium (Mg), calcium (Ca) and strontium (Sr). Examplesof Ni modifiers include those modifiers for Li and, in addition,aluminum (Al), manganese (Mn) and boron (B). Other examples of Nimodifiers include cobalt (Co) and titanium (Ti). Preferably, the lithiumnickelate is coated with LiCoO₂. The coating can be, for example, agradient coating or a spot-wise coating.

One particular type of a lithium nickelate that can be used in theinvention is represented by an empirical formula ofLi_(x3)Ni_(1−z3)M′_(z3)O₂ where 0.05<x3<1.2 and 0<z3<0.5, and M′ is oneor more elements selected from a group consisting of Co, Mn, Al, B, Ti,Mg, Ca and Sr. Preferably, M′ is one or more elements selected from agroup consisting of Mn, Al, B, Ti, Mg, Ca and Sr.

Another particular type of a lithium nickelate that can be used in theinvention is represented by an empirical formula ofLi_(x4)A*_(x5)Ni_((1−y4−z4))Co_(y4)Q_(z4)O_(a) where x4 is equal to orgreater than about 0.1 and equal to or less than about 1.3; x5 is equalto or greater than 0.0 and equal to or less than about 0.2; y4 is equalto or greater than 0.0 and equal to or less than about 0.2; z4 is equalto or greater than 0.0 and equal to or less than about 0.2; a is greaterthan about 1.5 and less than about 2.1; A* is at least one member of thegroup consisting of barium (Ba), magnesium (Mg) and calcium (Ca); and Qis at least one member of the group consisting of aluminum (Al),manganese (Mn) and boron (B). Preferably, y4 is greater than zero. Inone preferred embodiment, x5 is equal to zero, and z4 is greater than0.0 and equal to or less than about 0.2. In another embodiment, z4 isequal to zero, and x5 is greater than 0.0 and equal to or less thanabout 0.2. In yet another embodiment, x5 and z4 are each independentlygreater than 0.0 and equal to or less than about 0.2. In yet anotherembodiment, x5, y4 and z4 are each independently greater than 0.0 andequal to or less than about 0.2. Various examples of lithium nickelateswhere x5, y4 and z4 are each independently greater than 0.0 and equal toor less than about 0.2, can be found in U.S. Pat. Nos. 6,855,461 and6,921,609 (the entire teachings of which are incorporated herein byreference).

A specific example of the lithium nickelate isLiNi_(0.8)Co_(0.15)Al_(0.05)O₂. A preferred specific example isLiCoO₂-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O₂. In a spot-wise coatedcathode, LiCoO₂ doe not fully coat the nickelate core particle. Thecomposition of LiNi_(0.8)Cu_(0.15)Al_(0.05)O₂ coated with LiCoO₂ cannaturally deviate slightly in composition from the 0.8:0.15:0.05 weightratio between Ni:Co:Al. The deviation can range about 10-15% for the Ni,5-10% for Co and 2-4% for Al. Another specific example of the lithiumnickelate is Li_(0.97)Mg_(0.03)Ni_(0.9)Co_(0.1)O₂. A preferred specificexample is LiCoO₂-coated Li_(0.97)Mg_(0.03)Ni_(0.9)Co_(0.1)O₂. Thecomposition of Li_(0.97)Mg_(0.03)Ni_(0.9)Co_(0.1)O₂ coated with LiCoO₂can deviate slightly in composition from the 0.03:0.9:0.1 weight ratiobetween Mg:Ni:Co. The deviation can range about 2-4% for Mg, 10-15% forNi and 5-10% for Co. Another preferred nickelate that can be used in thepresent invention is Li(Ni_(1/3)Co_(1/3)Mn_(1/3))O₂, also called“333-type nickelate.” This 333-type nickelate optionally can be coatedwith LiCoO₂, as described above.

Suitable examples of lithium cobaltates that can be used in theinvention include Li_(1+x8)CoO₂ that is modified by at least one of Lior Co atoms. Examples of the Li modifiers are as described above for Liof lithium nickelates. Examples of the Co modifiers include themodifiers for Li and aluminum (Al), manganese (Mn) and boron (B). Otherexamples include nickel (Ni) and titanium (Ti) and, in particular,lithium cobaltates represented by an empirical formula ofLi_(x6)M′_((1−y6))Co_((1−z6))M′_(z6)O₂, where x6 is greater than 0.05and less than 1.2; y6 is equal to or greater than 0 and less than 0.1,z6 is equal to or greater than 0 and less than 0.5; M′ is at least onemember of magnesium (Mg) and sodium (Na) and M″ is at least one memberof the group consisting of manganese (Mn), aluminum (Al), boron (B),titanium (Ti), magnesium (Mg), calcium (Ca) and strontium (Sr), can beused in the invention. Another example of a lithium cobaltate that canbe used in the invention is unmodified Li_(1+x8)CoO₂, such as LiCoO₂. Inone specific embodiment, the lithium cobaltate (e.g., LiCoO₂) doped withMg and/or coated with a refractive oxide or phosphate, such as ZrO₂ orAl(PO₄).

It is particularly preferred that lithium oxide compounds employed havea spherical-like morphology, since it is believed that this improvespacking and other production-related characteristics.

Preferably, a crystal structure of each of the lithium cobaltate andlithium nickelate is independently a R-3m type space group(rhombohedral, including distorted rhombohedral). Alternatively, acrystal structure of the lithium nickelate can be in a monoclinic spacegroup (e.g., P2/m or C2/m). In a R-3m type space group, the lithium ionoccupies the “3a” site (x=0, y=0 and z=0) and the transition metal ion(i.e., Ni in a lithium nickelate and Co in a lithium cobaltate) occupiesthe “3b” site (x=0, y=0, z=0.5). Oxygen is located in the “6a” site(x=0, y=0, z=z0, where z0 varies depending upon the nature of the metalions, including modifier(s) thereof).

Examples of olivine compounds that are suitable for use in the inventionare generally represented by a general formula Li_(1−x2)A″_(x2)MPO₄,where x2 is equal to or greater than 0.05, or x2 is equal to or greaterthan 0.0 and equal to or greater than 0.1; M is one or more elementsselected from a group consisting of Fe, Mn, Co, or Mg; and A″ isselected from a group consisting of Na, Mg, Ca, K, Ni, Nb. Preferably, Mis Fe or Mn. More preferably, LiFePO₄ or LiMnPO₄, or both are used inthe invention. In a preferred embodiment, the olivine compounds arecoated with a material having relatively high electrical conductivity,such as carbon. In a more preferred embodiment, carbon-coated LiFePO₄ orcarbon-coated LiMnPO₄ is employed in the invention. Various examples ofolivine compounds where M is Fe or Mn can be found in U.S. Pat. No.5,910,382 (the entire teachings of which are incorporated herein byreference).

The olivine compounds typically have a small change in crystal structureupon charging/discharging, which generally makes the olivine compoundssuperior in terms of cycle characteristics. Also, safety is generallyhigh, even when a battery is exposed to a high temperature environment.Another advantage of olivine compounds (e.g., LiFePO₄ and LiMnPO₄) istheir relatively low cost.

Manganate spinel compounds have a manganese base, such as LiMn₂O₄. Whilethe manganate spinel compounds typically have relatively low specificcapacity (e.g., in a range of about 110 to 115 mAh/g), they haverelatively high power delivery when formulated into electrodes andtypically are safe in terms of chemical reactivity at highertemperatures. Another advantage of the manganate spinel compounds istheir relatively low cost.

One type of manganate spinel compounds that can be used in the inventionis represented by an empirical formula ofLi_((1+x1))(Mn_(1−y1)A′_(y2))_(2-x2)O_(z1), where A′ is one or more ofMg, Al, Co, Ni and Cr; x1 and x2 are each independently equal to orgreater than 0.01 and equal to or less than 0.3; y1 and y2 are eachindependently equal to or greater than 0.0 and equal to or less than0.3; z1 is equal to or greater than 3.9 and equal to or less than 4.1.Preferably, A′ includes a M³⁺ ion, such as Al³⁺, Co³⁺, Ni³⁺ and Cr³⁺,more preferably Al³⁺. The manganate spinel compounds ofLi_((1+x1))(Mn_(1−y1)A′_(y2))_(2−x2)O_(z1) can have enhanced cyclabilityand power compared to those of LiMn₂O₄. Another type of manganate spinelcompounds that can be used in the invention is represented by anempirical formula of Li_((1+x1))Mn₂O_(z1), where x1 and z1 are eachindependently the same as described above. Alternatively, the manganatespinel for the invention includes a compound represented by an empiricalformula of Li_(1+x9)Mn_(2−y9)O_(z9) where x9 and y9 are eachindependently equal to or greater than 0.0 and equal to or less than 0.3(e.g., 0.05≦x9, y9≦0.15); and z9 is equal to or greater than 3.9 andequal to or less than 4.2. Specific examples of the manganate spinelthat can be used in the invention include LiMn_(1.9)Al_(0.1)O₄,Li_(1+x1)Mn₂O₄, Li_(1+x7)Mn_(2−y7)O₄, and their variations with Al andMg modifiers. Various other examples of manganate spinel compounds ofthe type Li_((1+x1))(Mn_(1−y1)A′_(y2))_(2−x2)O_(z1) can be found in U.S.Pat. Nos. 4,366,215; 5,196,270; and 5,316,877 (the entire teachings ofwhich are incorporated herein by reference).

It is noted that the suitable cathode materials described herein arecharacterized by empirical formulas that exist upon manufacture oflithium-ion batteries in which they are incorporated. It is understoodthat their specific compositions thereafter are subject to variationpursuant to their electrochemical reactions that occur during use (e.g.,charging and discharging).

Examples of suitable non-aqueous electrolytes include a non-aqueouselectrolytic solution prepared by dissolving an electrolyte salt in anon-aqueous solvent, a solid electrolyte (inorganic electrolyte orpolymer electrolyte containing an electrolyte salt), and a solid orgel-like electrolyte prepared by mixing or dissolving an electrolyte ina polymer compound or the like.

The non-aqueous electrolytic solution is typically prepared bydissolving a salt in an organic solvent. The organic solvent can includeany suitable type that has been generally used for batteries of thistype. Examples of such organic solvents include propylene carbonate(PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethylcarbonate (DMC), 1,2-dimethoxyethane, 1,2-diethoxyethane,γ-butyrolactone, tetrahydrofuran, 2-methyl tetrahydrofuran,1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane,methylsulfolane, acetonitrile, propionitrile, anisole, acetate,butyrate, propionate and the like. It is preferred to use cycliccarbonates such as propylene carbonate, or chain carbonates such asdimethyl carbonate and diethyl carbonate. These organic solvents can beused singly or in a combination of two types or more.

Additives or stabilizers may also be present in the electrolyte, such asVC (vinyl carbonate), VEC (vinyl ethylene carbonate), EA (ethyleneacetate), TPP (triphenylphosphate), phosphazenes, biphenyl (BP),cyclohexylbenzene (CHB), 2,2-diphenylpropane (DP), lithiumbis(oxalato)borate (LiBoB), ethylene sulfate (ES) and propylene sulfate.These additives are used as anode and cathode stabilizers, flameretardants or gas releasing agents, which may make a battery have higherperformance in terms of formation, cycle efficiency, safety and life.

The solid electrolyte can include an inorganic electrolyte, a polymerelectrolyte and the like insofar as the material has lithium-ionconductivity. The inorganic electrolyte can include, for example,lithium nitride, lithium iodide and the like. The polymer electrolyte iscomposed of an electrolyte salt and a polymer compound in which theelectrolyte salt is dissolved. Examples of the polymer compounds usedfor the polymer electrolyte include ether-based polymers such aspolyethylene oxide and cross-linked polyethylene oxide, polymethacrylateester-based polymers, acrylate-based polymers and the like. Thesepolymers may be used singly, or in the form of a mixture or a copolymerof two kinds or more.

A matrix of the gel electrolyte may be any polymer insofar as thepolymer is gelated by absorbing the above-described non-aqueouselectrolytic solution. Examples of the polymers used for the gelelectrolyte include fluorocarbon polymers such as polyvinylidenefluoride (PVDF), polyvinylidene-co-hexafluoropropylene (PVDF-HFP) andthe like.

Examples of the polymers used for the gel electrolyte also includepolyacrylonitrile and a copolymer of polyacrylonitrile. Examples ofmonomers (vinyl based monomers) used for copolymerization include vinylacetate, methyl methacrylate, butyl methacylate, methyl acrylate, butylacrylate, itaconic acid, hydrogenated methyl acrylate, hydrogenatedethyl acrylate, acrlyamide, vinyl chloride, vinylidene fluoride, andvinylidene chloride. Examples of the polymers used for the gelelectrolyte further include acrylonitrile-butadiene copolymer rubber,acrylonitrile-butadiene-1-styrene copolymer resin,acrylonitrile-chlorinated polyethylene-propylenediene-styrene copolymerresin, acrylonitrile-vinyl chloride copolymer resin,acrylonitrile-methacylate resin, and acrlylonitrile-acrylate copolymerresin.

Examples of the polymers used for the gel electrolyte include etherbased polymers such as polyethylene oxide, copolymer of polyethyleneoxide, and cross-linked polyethylene oxide. Examples of monomers usedfor copolymerization include polypropylene oxide, methyl methacrylate,butyl methacylate, methyl acrylate, butyl acrylate.

In particular, from the viewpoint of oxidation-reduction stability, afluorocarbon polymer is preferably used for the matrix of the gelelectrolyte.

The electrolyte salt used in the electrolyte may be any electrolyte saltsuitable for batteries of this type. Examples of the electrolyte saltsinclude LiClO₄, LiAsF₆, LiPF₆, LiBF₄, LiB(C₆H₅)₄, LiB(C₂O₄)₂, CH₃SO₃L₁,CF₃SO₃Li, LiCl, LiBr and the like. Generally, a separator separates thepositive electrode from the negative electrode of the batteries. Theseparator can include any film-like material having been generally usedfor forming separators of non-aqueous electrolyte secondary batteries ofthis type, for example, a microporous polymer film made frompolypropylene, polyethylene, or a layered combination of the two. Inaddition, if a solid electrolyte or gel electrolyte is used as theelectrolyte of the battery, the separator does not necessarily need tobe provided. A microporous separator made of glass fiber or cellulosematerial can in certain cases also be used. Separator thickness istypically between 9 and 25 μm.

In some specific embodiments, a positive electrode can be produced bymixing the cathode powders at a specific ratio. 90 wt % of this blend isthen mixed together with 5 wt % of acetylene black as a conductiveagent, and 5 wt % of PVDF as a binder. The mix is dispersed inN-methyl-2-pyrrolidone (NMP) as a solvent, in order to prepare slurry.This slurry is then applied to both surfaces of an aluminum currentcollector foil, having a typical thickness of about 20 um, and dried atabout 100-150° C. The dried electrode is then calendared by a rollpress, to obtain a compressed positive electrode. When LiCoO₂ is solelyused as the positive electrode a mixture using 94 wt % LiCoO₂, 3%acetylene black, and 3% PVDF is typically used. A negative electrode canbe prepared by mixing 93 Wt % of graphite as a negative active material,3 wt % acetylene black, and 4 wt % of PVDF as a binder. The negative mixwas also dispersed in N-methyl-2-pyrrolidone as a solvent, in order toprepare the slurry. The negative mix slurry was uniformly applied onboth surfaces of a strip-like copper negative current collector foil,having a typical thickness of about 10 um. The dried electrode is thencalendared by a roll press to obtain a dense negative electrode.

The negative and positive electrodes and a separator formed of apolyethylene film with micro pores, of thickness 25 um, are generallylaminated and spirally wound to produce a spiral type electrode element.

In some embodiments, one or more positive lead strips, made of, e.g.,aluminum, are attached to the positive current electrode, and thenelectrically connected to the positive terminal of the batteries of theinvention. A negative lead, made of, e.g., nickel metal, connects thenegative electrode, and then attached to a feed-through device. Anelectrolyte of for instance EC:DMC:DEC with 1M LiPF₆, is vacuum filledin the cell casing of a lithium-ion battery of the invention, where thecell casing has the spirally wound “jelly roll.”

EXEMPLIFICATION Example 1 Preparation of the CIDs of the Invention

In this example, a process for manufacturing a CID as shown in FIG. 1,which includes a first conductive plate, a second conductive plate, aretainer between the two conductive plates, and an end plate.

1A. Preparation of First Conductive Plate 12

The first conductive plate (hereinafter “pressure disk”) was formed bystamping a flat sheet of Aluminum 3003 (H0) into a shape resembling ahat with angled edges, as shown in FIGS. 2A-2C. A flat aluminum sheethaving a thickness of about 0.005 inches (about 0.127 mm) (“d” in FIG.2C) was used. The flat aluminum sheet was first depressed using aconical punch with a flat top to thereby form a conical frustum, a basehaving a diameter of about 0.315 inches (about 8 mm) (“a” in FIG. 2C),and a flat top at a height of about 0.03 inches (about 0.762 mm) (“c” inFIG. 2C) from the base. The diameter of the flat top (“b” in FIG. 2C)was about 0.215 inches (about 5.46 mm). The angle of the frustumrelative to a plane parallel to the base was about 21 degrees. Thedepressed aluminum sheet was then trimmed for the base to have adiameter of about 0.500 inches (about 12.7 mm).

1B. Preparation of Second Conductive Plate 24

The second conductive plate (hereinafter “weld disk”) was manufacturedfrom aluminum in a progressive die. An aluminum stock (3003H14) whichwas about 0.020 inches (about 0.508 mm) thick was fed into theprogressive die where multiple stamping and coining operations produceda part with an outer diameter of about 0.401 inches (about 10.2 mm), aconcentric depression having a diameter of about 0.100 inches (about2.54 mm, “a” in FIG. 3C) and a thickness of about 0.003 inches (about0.0762 mm) (“c” in FIG. 3C). Two symmetric trough holes of about 0.040inches (about 1.02 mm) in diameter were made to the plate for pressurecommunication on both sides of the depression. The holes were located ata distance of about 0.140 inches (about 3.56 mm) from the center of theplate.

1C. Preparation of Retainer Ring 40

A retainer ring as shown in FIG. 1, FIG. 8A, and FIG. 8D wasmanufactured of polypropylene material by means of injection molding.The purpose of the retainer ring was to hold the weld disk at a fixeddistance to the pressure disk before, during, and after the reversal ofthe pressure disk. The reversal of the pressure disk occurred when theCID was activated. The retainer ring was also employed to ensure thatthe weld disk was electrically isolated from the pressure risk after itsreversal. The retainer ring included an over-mold feature which securedthe weld disk in place after it had been snapped into the retainer ring.

1D. Preparation of the End Plate 34

An end plate as shown in FIG. 4 can provide a space necessary foraccommodating the pressure disk and for the reversal of the frustum partof the pressure disk. In this example, the lid of a battery can wasemployed as the end plate. The end plate was manufactured from stampedAluminum 3003 series (H14).

For the space necessary for accommodating the pressure disk, a firstcylindrical embossment (or recess 36 in FIG. 4) was created by millingor alternatively stamping operation onto the lid. The diameter of theembossment (“a” in FIG. 4) was about 0.505 inches (about 12.8 mm), whichwas slightly larger than the outer diameter of the pressure disk (about0.500 inches (about 12.7 mm)). The depth of the first embossment (“b” inFIG. 4) was about 0.0045 inches (about 0.114 mm), which was slightlyless then the thickness of the pressure disk (about 0.005 inches (about0.127 mm)).

For the space necessary for accommodating the frustum portion of thepressure disk upon its reversal, a second concentric embossment (recess38 in FIG. 4) was similarly fabricated by milling or alternativelystamping. This second embossment had a diameter of about 0.325 inches(about 8.25 mm), which was slightly larger then the base diameter of thepressure disk frustum (about 0.315 inches (about 8.0 mm)). The secondembossment also had a depth of about 0.029 inches (about 0.737 mm) (“d”in FIG. 4), as measured from the first embossment, which was slightlylarger than the net height of the pressure disk (about 0.025 inches(about 0.635 mm), “c” in FIG. 3C), as measured from datum line at thebase of the frustum.

To accommodate a weld pin, a through hole, which was concentric with thetwo embossments, was made by drilling or punching. The hole had adiameter of about 0.100 inches (about 2.54 mm), which was large enoughto accommodate the weld pin to be used for support and cooling of thepressure disk during a spot welding operation described below.

1E. Pre-Cleaning of the Weld Disk, End Plate and Retainer Ring

Prior to assembly, the weld disk (24), end plate (34), and retainer ring(40) were degreased and cleaned with isopropanol (e.g., 90% isopropanol)in an ultrasonic cleaner. The cleaning was typically done for about 10minutes, and dried in low humidity environment or oven at about 70degrees Celsius.

1F. Assembly

The components of the CID were assembled as shown in FIG. 1. Thepressure disk (12) was placed in the first embossment (recess 36) of theend plate (34), with the conical frustum facing away from the end plate.A vacuum suction was used to pull the pressure disk tightly onto the endplate in order to provide good contact between the two parts. The twoparts were joined hermetically by means of penetration welding at themiddle circumferential region of base 20 of first conductive plate 12(e.g., position “a” shown in FIG. 1).

The assembled pressure disk/end plate was placed in a spot weld fixturewith a solid Copper (Cu) weld pin that penetrated the end plate througha hole. The weld pin was used to support and cool the pressure diskduring the spot welding operation later. The weld disk (24) was placedinto the retainer ring. The assembled weld disk/retainer ring wasmounted in the spot weld fixture to hold the weld disk/retainer ringassembly concentrically in place on top of the pressure disk. Thefixture provided adequate force to push the weld disk firmly onto thepressure disk, to the point of noticeable deformation of the pressuredisk and weld disk by the weld pin. The weld disk was attached to thepressure disk with two spot laser welding in the area deformed andsupported by the weld pin. During the welding operation, the pressuredisk was cooled via the weld pin.

Example 2 Preparation of the Battery of the Invention

Lithium-ion batteries were prepared using either 100% of Li_(1+x)CoO₂ (xis about 0-0.2), or a mixture that includes about 80 wt % ofLi_(1+x)CoO₂ (x is about 0-0.2) and about 20 wt % ofLi_(1+x9)Mn_((2−y9))O₄ (each of x9 and y9 is independently about0.05-0.15) as their active cathode materials. The cell thickness, cellwidth and cell height of the batteries were about 18 mm, about 37 mm andabout 65-66 mm, respectively. Anodes of the batteries were of carbon.About 5.5 wt % of biphenyl (BP) was included in the electrolytes of thebatteries. Al tabs and Ni tabs were employed as the cathode and anodetabs of the batteries, respectively. The Al tabs of the cathode werewelded onto the second conductive plate of the CID described above inExample 1. The Ni tabs of the anode of the battery were welded onto thefeed-through device of the battery (see FIG. 8A and FIG. 8D).

Example 3 CID Activation Tests

The CIDs prepared as described in Example 1, not installed in batterycells, were tested in this example. For these tests, a pressure testfixture was designed so that the CID side of the end plate (34) of theCIDs could be pressurized with compressed air or nitrogen to test theCID Release Pressure (CRP). The test pressure was started at about 5 bar(gauge), and increased in 0.5 bar increments. At each pressure setting,the end plate was kept under the test pressure for 10 seconds before thepressure increase. The pressure increase was done gradually between eachsetting so that the CRP could be observed with a resolution of a 0.1-0.2bar. The test results are summarized in FIG. 10. As shown in FIG. 10,the average gauge pressure of the CID trip was about 7.7 bar.

Example 4 CID Activation Tests in Lithium-Ion Batteries

4A. Lithium-Ion Batteries Including a Mixture of Li_(1+x)CoO₂ andLi_(1+x9)Mn_((2−y9))O₄

For the tests of the example, the lithium-ion batteries that employed amixture including about 80 wt % of Li_(1+x)CoO₂ and about 20 wt % ofLi_(1+x9)Mn_((2−y9))O₄ as their active cathode materials, as describedin Example 2, were overcharged at 2C charge rate. Generally, “1C”represents a charge rate that would fully recharge the cell, from 1% to100% state of charge, in one hour. Thus, with the “2C” rate, the cellwould be fully recharged in 30 minutes. The CIDs of the tested batterieswere activated between about 5 and 7.5 minutes in average after the fullcharge of about 4.2V

FIG. 11 shows pressure rise rates with respect to the overchargingvoltages. In the tested batteries, the internal pressure was increasedat a rate of about 5 bar per minute at about 4.68 V of overcharge.

FIG. 12 shows the cell skin temperatures measured when the CIDs of thetested batteries were activated. As shown in FIG. 12, the average celltemperature at the time of the CID activation was about 52.8° C.Generally, after the CID activation, the cell temperatures were keptincreasing for a while by another 10-15° C. and then started to drop.FIG. 13 shows the results of the peak skin temperatures of the testedbatteries. As shown in FIG. 13, the average peak skin temperature forthe tested batteries was about 65.1° C.

The cell pressures (bar) were calculated based upon the measured cellthickness during the overcharge tests. For the tested cells, the averagecalculated gauge pressure of the CID trip was about 7.9 bar. FIG. 14shows the calculated pressures versus the measured cell skintemperatures of one of the tested batteries. As shown in FIG. 14, theCID of the battery was activated after about 5-6 minutes afterovercharging, and the cell skin temperature measured at that time wasabout 55° C. As discussed above, the cell temperature of the battery waskept increasing for a while by another 10-15° C., and then started todrop.

4B. Lithium-Ion Batteries Including 100% of Li_(1+x)CoO₂

For the tests of the example, the lithium-ion batteries that employed100% of Li_(1+x)CoO₂ as their active cathode materials, as described inExample 2, were employed. The batteries were overcharged at 2C chargerate, as described above in Example 4A. The average cell skintemperature of the batteries when their CIDs were activated was about65° C., and the cell temperatures further increased up to about 72° C.FIG. 15 shows an average cell skin temperature of the tested batteriesof Examples 4A and 4B when their CIDs were activated, where cure Arepresents batteries of Example 4A and curve B represents batteries ofExample 4B.

4C. Control Tests for Lithium-Ion Batteries with Commercially AvailableCIDs

As a comparison, two 18650 commercially available cylindrical cells(Sony US18650GR: cells A and B of the same model), each of whichemployed standard 100% of Li_(1+x)CoO₂ cell chemistry and a CID, weretested. These cells were overcharged at 2C charge rate, as describedabove in Example 4A. The CIDs of the Sony cells were activated at atemperature between about 94-96° C. and at about 110-120° C., as shownin FIG. 15 (curve C for 18650 cell A and curve D for 18650 cell B). Thetemperature of the cells after their CID activation continued toincrease and reached about 110-126° C. which were very close to typicalthermal runaway temperatures.

Additional two 18650 commercially available cylindrical cells (SonyUS18650GR: cells C and D of the same model), each of which employedstandard 100% of Li_(1+x)CoO₂ cell chemistry and a CID, were tested. TheCIDs of these Sony cells were pressure tested, as described above inExample 3. The CIDs activated at about 13.8-14.3 bar (gauge pressure)(cell C at about 14.3 bar, cell D at about 13.8 bar).

Based upon the results of Examples 4A-4B and control Example 4C, themaximum cell temperatures reached in the batteries of the invention weresignificantly lower than the control 18650 cells with conventional CIDs.It is noted that the batteries of Examples 4A and 4B had greater thantwice the volume of control 18650 cells, and yet exhibited much lowerCID activation temperatures and pressures. Such lower CID activationtemperatures and pressures, in turn, generally relate to reducing thelikelihood of thermal runaway in the cells. Thus, the CIDs of theinvention can enable batteries or cells, particularly relatively largebatteries or cells (e.g., larger than 18650 cells) to exhibit highlyimproved safety-related characteristics.

INCORPORATION BY REFERENCE

U.S. patent application, filed on Jun. 22, 2007 under Attorney's DocketNo. 3853.1012-001, which is entitled “Integrated Current-InterruptDevice For Lithium-Ion Cells”; International Application, filed on Jun.22, 2007 under Attorney's Docket No. 3853.1001-015, entitled“Lithium-Ion Secondary Battery”; U.S. Provisional Application No.60/816,775, filed Jun. 27, 2006; U.S. Provisional Application No.60/717,898, filed on Sep. 16, 2005; International Application No.PCT/US2005/047383, filed on Dec. 23, 2005; U.S. patent application Ser.No. 11/474,081, filed on Jun. 23, 2006; U.S. patent application Ser. No.11/474,056, filed on Jun. 23, 2006; U.S. Provisional Application No.60/816,977, filed on Jun. 28, 2006; U.S. patent application Ser. No.11/485,068, filed on Jul. 12, 2006; U.S. patent application Ser. No.11/486,970, filed on Jul. 14, 2006; U.S. Provisional Application No.60/852,753, filed on Oct. 19, 2006; U.S. Provisional Application No.61/125,327, filed on Apr. 24, 2008; U.S. Provisional Application No.61/125,281, filed on Apr. 24, 2008; and U.S. Provisional Application No.61/125,285, filed on Apr. 24, 2008 are all incorporated herein byreference in their entirety.

EQUIVALENTS

While this invention has been particularly shown and described withreferences to example embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. A pressure response device comprising: a flange portion; a centralportion, the central portion having an inlet side and an outlet side; anangled frustum portion provided between the flange portion and thecentral portion; and wherein the angled frustum portion is configured toactivate upon experiencing a predetermined pressure differential causingthe movement of the central portion.
 2. The system of claim 1, whereinupon activation, displacement of the central portion causes the openingof an electric circuit.
 3. The system of claim 1, wherein uponactivation, displacement of the central portion causes the closing of anelectric circuit.
 4. The device of claim 1, wherein an angle between theangled frustum portion and a plane defined by the flange portion isbetween about 10 degrees and about 60 degrees.
 5. The device of claim 1,wherein an angle between the angled frustum portion and a plane definedby the flange portion is between about 15 degrees and about 35 degrees.6. The device of claim 1, wherein the angled frustum portion is in theshape of a symmetrical truncated cone.
 7. The device of claim 1, whereinthe angled frustum portion is in the shape of an irregular truncatedcone.
 8. The device of claim 1, wherein the angled frustum portion is inthe shape of an irregular truncated dome.
 9. The device of claim 1,wherein the central portion further comprises an indentation.
 10. Thedevice of claim 9, wherein the indentation defines a cavity in the inletside of the central portion and wherein the indentation defines a nipplein the outlet side of the central portion.
 11. The device of claim 9,wherein the indentation defines a cavity in the outlet side of thecentral portion and wherein the indentation defines a nipple in theinlet side of the central portion.
 12. The device of claim 1, whereinthe central portion exhibits a substantially flat shape.
 13. The deviceof claim 1, wherein the pressure response device is constructed from thegroup of materials consisting of stainless steel, aluminum, or nickeland its alloys.
 14. The device of claim 1, wherein the pressure responsedevice is constructed from the group of manufacturing techniquesconsisting of forming or stamping metal coil, forming or stamping sheetmaterial, machining metal, casting, or molding.
 15. A pressure responsesystem comprising: a pressure response device, the pressure responsedevice including a flange portion, a central portion, and an angledfrustum portion provided between the flange portion and the centralportion; wherein the central portion is substantially flat; aprojection, the projection being operably attached to the centralportion; wherein the angled frustum portion is configured to activatewithout rupturing upon experiencing a predetermined pressuredifferential causing the movement of the central portion; and whereinthe activation of the frustum portion causes the projection to indicatea pressure response.
 16. A pressure response system comprising: apressure response device, the pressure response device including aflange portion, a central portion, and an angled frustum portionprovided between the flange portion and the central portion, wherein theangled frustum portion is configured to activate upon experiencing apredetermined pressure differential causing the movement of the centralportion; a conductor, the conductor configured to make an electricalwire connection with the central portion before the angled frustumportion activates; and wherein the electrical wire connection isinterrupted when the angled frustum portion activates.
 17. A batterydevice comprising: an exterior contact terminal; a pressure responsemember positioned within the battery device, the pressure responsemember having a first configuration and a second configuration; thepressure response member including a central portion surrounded by anangled frustum portion; and wherein the pressure response member formspart of an electrical conducting path within the battery device in thefirst configuration and wherein upon experiencing a predeterminedpressure condition with the battery device, the pressure response memberachieves the second configuration and no longer forms part of anelectrical conducting path within the battery device.
 18. The device ofclaim 17, wherein the central portion is configured to activate withoutrupturing upon experiencing the force of a predetermined pressurecondition.
 19. A method of testing a pressure response systemcomprising: providing a pressure response member including a flangeportion, a central portion, and an angled frustum portion between theflange portion and the central portion; applying an increasing pressuredifferential to one surface of the central portion; and recording thepressure at which the angled frustum portion activates.
 20. A method ofresponding to an overpressure situation, comprising: providing apressure response member including a flange portion, a central portion,and an angled frustum portion between the flange portion and the centralportion, wherein the pressure response member has a first configurationand a second configuration; exposing the pressure response member in thefirst configuration to a pressure source, such that the pressureresponse member responds to a predetermined pressure in the pressuresource by taking the second configuration.
 21. The pressure responsedevice of claim 1, wherein the angle between the angled frustum portionand a plane defined by the flange portion is bout 25 degrees.